Field of the Invention
The present invention relates to an inlet air filter arrangement, to an inlet air filter cartridge, and to equipment for supporting multiple inlet air filter cartridges for a gas turbine or a combustion turbine.
Description of the Related Art
The operation of a gas turbine or a combustion turbine requires the ingestion of a large volume of ambient air. Filtration of the ambient air by using an inlet air filter system is required in order to protect the gas turbine or combustion turbine from the negative effects of contaminated air, which include foreign object damage, erosion, and turbine blade fouling. The inlet air filter system, which may be formed of different stages, usually comprises pulse cleaned or static filter cartridges.
Generally, the inlet air filter system comprises a housing with a tubesheet that separates the inlet side and the outlet side of the housing. The tubesheet typically comprises a large number of tubesheet openings, such as 300 to 1000 openings, each of which is associated with a filter cartridge. The filter cartridges have an open end sealed around the respective tubesheet opening and a closed end at the inlet side of the housing. The filter cartridges are usually conical or cylindrical cartridges, or combinations of these.
As a result of introducing an ambient air stream through the inlet filter system, particulate matter collects on the filter cartridges and tends to increase the flow resistance of the filter system. The filters can be cleaned by using, for example, a reverse gas pulse cleaning approach. In the reverse gas pulse cleaning approach, gas pulses, typically, air pulses, are introduced periodically against the direction of the normal air stream through the tubesheet openings into the filter cartridges. The gas pulses remove particulate matter collected on the inlet surface of the filter cartridges, which tends to reduce the flow resistance of the filter system. It is, however, eventually necessary to replace used filter cartridges by new ones. The required replacing frequency, which depends, for example, on the prevailing operating conditions and on the dust holding capacity of the filtration system, may vary from about one to about three years in the case of pulse cleaned filters, to as high as about one to about three times in a year in the case of static filters. The cost of the replacement filters, as well as the labor cost and logistic costs related to the replacement and transport of the filters, may thus be a significant part of the life cycle cost of a gas turbine or a combustion turbine plant.
According to a conventional method, gas turbine or combustion turbine inlet air filters are attached to the tubesheet by permanently installed support structures, such as yokes or tripods, which are supported by the tubesheet and extend to the inlet side of the housing within the interior of the associated filter cartridge. Filter support yokes are shown, for example, in the brochure “How to Service Filters on GDX & GDS Systems, GTS-501”, available from the Internet page http://www.donaldson.com/en/gasturbine/support/datalibrary/index.html. A replacement filter cartridge is connected to the tubesheet by carefully sliding it on the support structure, and securing the closed end of the filter cartridge to the top end of the support structure so as to seal the open end of the filter cartridge to the tubesheet. Such a support structure make it possible to use simple filter cartridges without special elements for connecting them to the tubesheet. However, the installing of a new filter cartridge, which may, for example, consist of two pieces having a length of about 66 centimeters (26 inches), to the support structure is relatively complicated. There is also a risk of damaging the support structure or the filter cartridge, especially, the filter media, by accidental impact with the support structure. The protruding support structure is a potential safety hazard for maintenance personnel replacing the filter cartridges. The additional seal between the two cartridge pieces is a potential point of failure in the system and a potential path for particulates to bypass the filters and to damage the gas turbine or the combustion turbine. The loose hardware utilized to secure the filter cartridge to the support structure can potentially fail, or accidentally be left in the filter house, which could damage the gas turbine or the combustion turbine.
It is also known to connect the filter cartridges to the tubesheet by the aid of a connecting member of the filter cartridge protruding from the open end of the filter cartridge. The tubesheet then comprises complementary connecting elements enabling the fixing of the filter cartridge to the tubesheet. The connecting member of the filter cartridge may consist of separate connecting wings or a sleeve with helical slots, which wings or slots are then connected to corresponding studs in the connection elements of the tubesheet openings. An example of a filter cartridge with connecting wings protruding from the open end of the filter cartridge is shown in the brochure “Pneuma-Pulse Cross Flow Cartridges”, available from the Internet page http://www.pneumafil.com/gas_turbine_inlet_air_filtration/category/literature. A disadvantage of this connection mechanism is that the connection member protruding from the open end of the filter cartridge increases the length of the filter cartridge, which gives rise to increased logistical costs of the replacement. The protruding connecting member may also be damaged during the transport and installation of the filter cartridges, and is also a potential safety hazard as the protruding connecting member may accidentally contact installation personnel. Also, the connecting member in the filter cartridge increases the material costs and the manufacturing costs of the filter cartridge by an amount that is significant due to the high number of the replaced filter cartridges. Also, the connecting members in this connection mechanism are individually attached to the open end of the filter cartridge, which provides minimal structural support when the filters are installed in the horizontal position.
An object of the invention is to provide a gas turbine or a combustion turbine inlet air filter arrangement, an inlet air filter cartridge, and equipment for supporting inlet air filter cartridges, in which at least some of the disadvantages of the prior art are minimized.